Background: Almost half of Veterans with localized prostate cancer (the most common non-cutaneous malignancy among US men) receive inappropriate, wasteful imaging. The VHA Blueprint for Excellence prioritizes increasing operational effectiveness. Prior studies seeking to limit inappropriate imaging did not assess barriers and achieved mixed results. Our team has explored the causes of guideline-discordant prostate cancer imaging and found that 1) patients with newly diagnosed prostate cancer have little concern for radiographic staging but rather focus on treatment, 2) physician trust imaging guidelines but are apt to follow their own intuition, fear medico-legal consequences, and succumb to influence from colleagues who image frequently. In spite of such discrepant v iews, most VHA physicians suggested or supported a large-scale effort to improve imaging use across VHA. Intervention: We propose a multi-site, stepped wedge, cluster-randomized trial to determine the effect of a physician-focused behavioral intervention on VHA prostate cancer imaging use. The multi-level intervention, developed according to the Theoretical Determinants Framework, combines traditional physician behavior change methods with novel methods of communication and data collection. The intervention consists of three components: 1) a system of audit and feedback to clinicians informing individual clinicians and their sites about how their behavior compares to their peers? and to published guidelines 2) a program of academic detailing with the goal to educate providers about prostate cancer imaging, and 3) a CPRS Clinical Order Check for potentially inappropriate imaging. The intervention will be introduced to 10 participating geographically-distributed study sites. Analysis Plan: We will assess imaging rates 6 months prior to the intervention and 3 months following the intervention. The study?s specific aims seek to understand the effects of the intervention on 1) facility-level prostate cancer imaging rates, 2) physician experience with and perceptions of the intervention and its implementation, and 3) the costs of both implementing the intervention and affecting change in imaging use. These aims will support a subsequent intervention to improve guideline-concordant imaging across VHA. Experience gained through this project will be leveraged to improve guideline-concordant care and increase operational effectiveness in other domains. Importance: This project seeks to describe and analyze the implementation of a behavioral intervention to improve prostate cancer care. This theory-based intervention builds on prior work identifying barriers to guideline-concordant prostate cancer imaging in VHA (CDA 11-257) and addresses these at three levels: individual (audit and feedback with VHA Cancer Care Cube data), facility (academic detailing) and system (CPRS Order Check). The team will assess the intervention?s cost impact and providers? experiences in preparation for a subsequent large -scale VHA implementation project optimizing the operational effectiveness of prostate cancer imaging across VHA. The current application is an opportunity to leverage VHA?s state-of-the-art, integrated healthcare delivery system to implement a carefully designed, theory-based behavioral intervention to reduce harmful, inappropriate care, increase appropriate care to those who truly need it, and simultaneously save money for the healthcare system.